A complete sun protection routine has three parts. Sunscreen on skin. Fabric over as much skin as possible. And then two tissues that neither of those addresses: the eyes and the lips.
They are missed for the same practical reason. You cannot put sunscreen in your eyes, and you do not want it on your mouth. So both get skipped, in every activity, by almost everyone.
The eye is an exposed organ
The surface of the eye takes ultraviolet directly. The most immediate effect is photokeratitis, an inflammation of the cornea that develops some hours after exposure and is genuinely painful. It is the same phenomenon as snow blindness and as welder's flash. It is most likely in high ultraviolet environments with strong reflection, which is why snow and open water are the classic settings.
Longer term ultraviolet exposure of the eye and the surrounding tissue is a subject the eye health and public health bodies address, and it is a reason eye protection is recommended alongside skin protection rather than as an optional extra. We do not describe clinical conditions or their management here, and anyone with a concern about their eyes should speak to an optometrist or a GP.
The standard behind sunglasses
UV400
What it certifies
A widely used marking indicating that a lens blocks ultraviolet up to 400 nanometres, which covers the ultraviolet A and B ranges relevant to eye protection. It is a useful thing to see on a lens.
What it does not
It is not the same as conformity with the sunglasses standard. In the UK and Europe, sunglasses are covered by BS EN ISO 12312-1, which addresses ultraviolet transmittance along with filter categories, optical quality and other requirements. A marking alone is not a substitute for a product meeting the standard, and darkness of tint is not an indicator of ultraviolet protection at all.
BS EN ISO 12312-1 is the standard covering sunglasses and similar eyewear for general use, and it deals with ultraviolet transmittance, filter categories, optical requirements and related matters. Filter categories describe how much visible light a lens transmits, running from very light tints through to very dark lenses intended for intense conditions such as glaciers, with the darkest category not suitable for driving.
Two things follow that surprise people.
Dark does not mean protective. Tint darkness is about visible light. Ultraviolet protection is a separate property. A very dark lens with poor ultraviolet performance is arguably worse than no lens at all, because it opens the pupil while letting ultraviolet through.
Fit matters as much as the lens. Ultraviolet arriving from the side and from below, particularly reflected off water or snow, goes around a small lens. Wraparound frames and side coverage exist for that reason. See our note on reflected ultraviolet.
Where eye protection matters most
- Snow, at altitude. The highest risk environment for photokeratitis, and the one where cold removes any warning. See ski touring.
- Open water. Constant glare off the surface, all day. See sailing and paddlesports.
- Bright sand. Reflective and usually accompanied by a long stationary day.
- Any activity where you squint for hours, which is a comfort and performance issue as well as a protective one.
A note on children: eye protection for children is often treated as a novelty item, and the eye's exposure does not distinguish by age. Properly rated eyewear for children exists and is worth having on snow and water.
Lips burn easily and are almost never protected
The lip surface is thin, has very little of the pigment that provides some protection elsewhere on the body, and sits prominently on the face. It also gets licked, wiped, pressed against a bottle and dried by wind, all of which remove anything applied to it.
Wind makes it worse, because chapped and cracked lips are damaged before ultraviolet is considered. The combination of wind and strong sun, which is exactly what sailing, skiing, cycling and hill walking deliver, is the hardest thing lips encounter.
What actually works
- A lip product carrying a sun protection factor, which is a distinct product category rather than a general lip balm.
- Carried somewhere reachable with gloves on, because otherwise it stays in a bag.
- Reapplied far more often than skin, because everything removes it: drinking, eating, wiping, licking, wind.
- Applied to the whole lip and slightly beyond the border, which is where people miss.
The lower lip takes more sun than the upper, because it faces upwards. That asymmetry is worth knowing and is why lower lips are the ones that crack and blister.
And the ones next door
The sites immediately adjacent to eyes and lips, the eyelids, the skin under the eyes, the nose, the ears, are the same kind of problem: small, awkward, uncomfortable to apply to, and consistently missed. Our note on the scalp, ears and the places everyone misses covers them.
Prescription lenses, contact lenses and cheap frames
Three practical points that come up constantly and are rarely addressed together.
Prescription sunglasses. A prescription lens can be made with ultraviolet protection, and clear prescription lenses frequently include it too. It is worth asking your optician directly rather than assuming, because it is a property of the lens material and any coating rather than of the tint.
Contact lenses. Some contact lenses include ultraviolet blocking. A lens covers the cornea and not the surrounding tissue, so it is not a substitute for eyewear, which also protects the eyelids and the skin around the eye. Those are among the sites reflected ultraviolet reaches on snow and water.
Very cheap sunglasses. The concern is not price, it is whether a product meets the standard. A dark lens without adequate ultraviolet performance opens the pupil while admitting ultraviolet, which is the one combination worth actively avoiding. Buying from a source that stands behind conformity with the standard is the practical answer.
Children, and the argument for making it normal
Eye protection for children tends to be treated as a novelty rather than as equipment, and the eye's exposure does not distinguish by age. On snow and on water in particular, properly rated eyewear for children is available and is worth having. The habit is also easier to establish early than to introduce later, which is the same argument that applies to hats. Public guidance from the NHS and from Cancer Research UK addresses children and sun exposure directly, and it is the right place to read further.
Wind, and why lips fail first in the mountains
Lips are the one tissue where two environmental stresses act on the same surface at once. Wind dries and cracks, which damages the surface layer before ultraviolet is considered, and a cracked lip has lost even the modest barrier it started with. Cold makes it worse by reducing how often anyone wants to take a glove off to do anything about it.
That combination is exactly what a hill day, a ski tour, a long ride and a day on the water all deliver. It is the reason lip damage is so characteristic of those activities and so rare in ordinary summer life, and it is why lip protection belongs in a pocket rather than in a bag.
What is not verifiable
We do not test eyewear, name products, or make claims about clinical outcomes. We do not tell you what any particular symptom means. What we can tell you is which standard applies, what the marking on a lens does and does not signify, and which environments produce the exposure. Anything about your eyes belongs with an optometrist or a GP.
The one line version
Buy eyewear that meets the standard rather than eyewear that looks dark, wear it from the start of the day on snow and water, and treat lip protection as a piece of kit you carry rather than something you might have somewhere.